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        검색결과 93

        1.
        2023.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aluminum alloys, known for their high strength-to-weight ratios and impressive electrical and thermal conductivities, are extensively used in numerous engineering sectors, such as aerospace, automotive, and construction. Recently, significant efforts have been made to develop novel aluminum alloys specifically tailored for additive manufacturing. These new alloys aim to provide an optimal balance between mechanical properties and thermal/ electrical conductivities. In this study, nine combinatorial samples with various alloy compositions were fabricated using direct energy deposition (DED) additive manufacturing by adjusting the feeding speeds of Al6061 alloy and Al-12Si alloy powders. The effects of the alloying elements on the microstructure, electrical conductivity, and hardness were investigated. Generally, as the Si and Cu contents decreased, electrical conductivity increased and hardness decreased, exhibiting trade-off characteristics. However, electrical conductivity and hardness showed an optimal combination when the Si content was adjusted to below 4.5 wt%, which can sufficiently suppress the grain boundary segregation of the α- Si precipitates, and the Cu content was controlled to induce the formation of Al2Cu precipitates.
        4,000원
        3.
        2023.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        인공위성은 최첨단 기술로써 시공간적 관측제약이 적어 해양 사고에 효과적 대응과 해양 변동 특성 분석 등으로 각국의 국가 기관들이 위성 정보를 활용하고 있다. 하지만 고해상도 위성 관측 기반 해수면 온도 자료(Operational Sea Surface Temperature and Sea Ice Analysis, OSTIA)는 위성의 기기적, 또는 지리적 오류와 구름으로 인해 낮게 관측되거나 공백으로 처리되며 이를 복원하기까지 수 시간이 소요된다. 본 연구는 최신 딥러닝 기반 알고리즘인 LaMa 기법을 활용하여 결측된 OSTIA 자료를 복원하고, 그 성능을 기존에 이용되어 온 세 가지 영상처리 기법들의 성능과 비교하여 평가하였다. 결정계수(R²)와 평균절대오차(MAE) 값을 이용하여 각 기법의 위성 영상 복원 성 능을 평가한 결과, LaMa 알고리즘을 적용하였을 때의 R²과 MAE 값이 각각 0.9 이상, 0.5℃ 이하로, 기존에 사용되어 온 쌍 선형보간법, 쌍 삼차보간법, DeepFill v1 기법을 적용한 것보다 더 우수한 성능을 보였다. 향후에는 현업 위성 자료 제공 시스템에 LaMa 기법을 적용하여 그 가능성을 평가해 보고자 한다.
        4,000원
        4.
        2023.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aluminum alloys are widely utilized in diverse industries, such as automobiles, aerospace, and architecture, owing to their high specific strength and resistance to oxidation. However, to meet the increasing demands of the industry, it is necessary to design new aluminum alloys with excellent properties. Thus, a new method is required to efficiently test additively manufactured aluminum alloys with various compositions within a short period during the alloy design process. In this study, a combinatory approach using a direct energy deposition system for metal 3D printing process with a dual feeder was employed. Two types of aluminum alloy powders, namely Al6061 and Al-12Cu, were utilized for the combinatory test conducted through 3D printing. Twelve types of Al-Si-Cu-Mg alloys were manufactured during this combinatory test, and the relationship between their microstructures and properties was investigated.
        4,000원
        6.
        2022.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Aluminum alloys are extensively employed in several industries, such as automobile, aerospace, and architecture, owing to their high specific strength and electrical and thermal conductivities. However, to meet the rising industrial demands, aluminum alloys must be designed with both excellent mechanical and thermal properties. Computer-aided alloy design is emerging as a technique for developing novel alloys to overcome these trade-off properties. Thus, the development of a new experimental method for designing alloys with high-throughput confirmation is gaining focus. A new approach that rapidly manufactures aluminum alloys with different compositions is required in the alloy design process. This study proposes a combined approach to rapidly investigate the relationship between the microstructure and properties of aluminum alloys using a direct energy deposition system with a dual-nozzle metal 3D printing process. Two types of aluminum alloy powders (Al-4.99Si-1.05Cu-0.47Mg and Al-7Mg) are employed for the 3D printing-based combined method. Nine types of Al-Si-Cu-Mg alloys are manufactured using the combined method, and the relationship between their microstructures and properties is examined.
        4,000원
        8.
        2021.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study examined the quality characteristics of yanggaeng with rice germ; it was incorporated into yanggaeng at different levels (containing 5% rice germ, 10% rice germ, 15% rice germ, and 20% rice germ) based on the total weight of red bean extracts. For analyzing the quality characteristics of yanggaeng, moisture content, hardness, color, antioxidant activity, total polyphenol content, reducing sugar, and vitamin E were determined. There was no significant difference in the moisture content and hardness except in the control. For color, lightness and yellowness of yanggaeng increased as the concentration of the powder was increased, whereas there was no significant difference in redness. As the rice germ powder was increased, total polyphenol content and antioxidant activity increased significantly, whereas reducing sugar decreased. Especially, total vitamin E, including isomers, increased as the concentration of the powder increased from 0.41 mg/100 g to 4.03 mg/100 g. Therefore, it could be possible to develop processed products with functional snack for yanggaeng prepared by adding 10% rice germ.
        4,000원
        14.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        This study analyzed the quality characteristics of Soksungjang combined with sorghum koji, according to the amount of sorghum added and the length of the fermentation period. The moisture content of Soksungjang was the lowest in the control group when there was no sorghum koji added, but gradually increased as the amount of added sorghum koji increased. The reduction in the sugar content of sorghum Soksungjang did not change according to the fermentation period of the control group, but increased alongside the fermentation period when sorghum koji was added to Soksungjang. The amino nitrogen content increased from 67.20-80.73 mg% from the beginning of the fermentation period to 173.13-383.60 mg% at the end of the fermentation period, and the total polyphenol content increased from 260.25-351.28 mg% from the beginning of the fermentation period to 567.28 mg%-674.93 mg% to the end of the fermentation period. DPPH radical scavenging activity also increased as the fermentation period elapsed, and ABTS radical scavenging activity increased and then decreased slightly over the fermentation period. The antioxidant activity was the highest in the Soksungjang mixture with a 10% concentration of sorghum koji.
        4,000원
        15.
        2021.04 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Centella asiatica (CA) has been used as a nutritional plant as well as a traditional herbal medicine around the world. This study, quality component (proximate composition, total polyphenol, and triterpenoid compound), and antioxidant and anti-inflammatory activities of CA dried using various methods were investigated. Proximate compositions of CA with different drying methods included a large amount of carbohydrates, crude protein, crude ash, and crude fiber. Among the drying methods, cold drying provided the highest total polyphenol content and antioxidant activity, while hot-air drying at 75℃ provided the lowest total polyphenol content and antioxidant activity. In addition, when the major triterpenoid compounds of CA were analyzed, the highest content of asiaticoside of triterpenoid glycoside was obtained with all drying methods. With respect to the total triterpenoid, the highest content was obtained with cold drying (68.8 mg/g) whereas natural drying (31.4 mg/g) provided the lowest content. In anti-inflammatory activity of LPS-stimulated RAW 264.7 cells, EtOH extract of cold drying showed a significantly higher inhibitory activity in comparison to the other drying methods. In conclusion, it is considered that the cold drying method is suitable for industrial preparation of functional materials with high physiological ingredients, and antioxidant and anti-inflammatory activities from CA.
        4,000원
        16.
        2021.03 KCI 등재 구독 인증기관 무료, 개인회원 유료
        화상병균(Erwinia amylovora)에 의해 발생하는 과수 화상병은 주로 사과, 배 등의 장미과 식물에서 발병한다. 과수 화상병은 국내에서 금지 병원균으로 지정되어 있으며, 2015년 경기도 안성의 배과수원에서 최초 발견되었다. 그러나, 현재까지 근본적인 방제약제가 없는 상황으로 발생지는 매몰이 최선의 방법으로 여겨진다. 따라서 본 연구에서는 2019년을 기준으로 충북지역의 과수 화상병 발생 원인 분석을 통하여 발생 경로 차단을 위한 역학조사를 실시하였다. 1. 충주시 등 3개 시군의 전체 221농가 141ha에서 과수 화상병이 발생하였으며, 세부적인 연도별 발생현황은 2015년(2농가 1ha), 2018년(74농가 51.5ha), 2019년(145농가 88.9ha) 로 나타났다. 2. 과수 화상병의 발생시기는 주로 5월부터 8월 사이로 나타났으며, 특히 6월(73.8%)이 가장 많이 발생하였으며, 7월 (17.2%), 5월(7.6%), 8월(1.4%)순으로 나타났다. 3. 과수 화상병 발생 의심 신고 후 확진 매몰까지 소요기간은 11.9일이었고, 발생에서 매몰까지의 기간은 최단 5일에서 최장 19일로 조사되었다. 4. 병원균의 최초 발생지로부터의 확산 거리는 평균 21 km로 나타났으며 가장 먼거리는 음성군 비산면으로 34 km였다.
        4,000원
        17.
        2019.12 KCI 등재 구독 인증기관 무료, 개인회원 유료
        PURPOSES: This study aims to suggest improvements to the management implementation plan for privately-financed roads. METHODS: We reviewed the establishment procedures and contents of the management implementation plan for expired businesses and analyzed the limits of detailed instructions. Additionally, we created a checklist including the needs of competent authorities to solve practical matters. Furthermore, we introduced the analytic hierarchy process (AHP) method to reflect aspects that were not covered in the detailed instructions. RESULTS: We suggested criteria for the decision-making structure system using the AHP method for efficient decision-making between the operation under government management and contracting-out. CONCLUSIONS: The proposed AHP method can consider other alternatives that are not proposed in the previous detailed instructions. However, further study is required with regard to the redundancy verification and appropriateness of weights of the evaluation items.
        4,200원
        18.
        2016.10 KCI 등재 구독 인증기관 무료, 개인회원 유료
        Method of characteristic(MOC) has been widely used as a transient analysis technique for pressurized pipeline systems. There are substantial studies using MOC for the water hammer triggered through instantaneous valve closures, pump stoppage and pump startup for pipelines systems equipped with a centrifugal pump. Considering restrictions of MOC associated with courant number condition for complicated pipeline systems, an impulse response method(IRM) was developed in the frequency domain. this study implements the impact of centrifugal pump using transfer function in frequency domain approach. Using pump performance curve and the affinity law, this study formulated transfer functions which relate complex pressure head at upstream of pump system to that of downstream location. Simulations of simple reservoir-pump-valve system using IRM with formulated transfer function were similar to those obtained through MOC.
        4,000원
        19.
        2015.06 KCI 등재 구독 인증기관 무료, 개인회원 유료
        In this paper through the study of Hyupgoksogun(「夾谷笑君」), which dealt with the incident of the murder of the actor in Je(齊) dynasty when Confucius was in the office during No(魯) dynasty and through the analysis of the speech of the actors in the following ages of Han(漢) and North-south dynasty(南北朝), it could be confirmed that the structure of the conflict between the actors and Confucianism changed from the one-way victory of Confucianism to the gradual strengthening of the actors. In the speeches of the actors of Dang(唐) and Northern Song(北宋) periods the bantering of Confucianism is general, distinct, and different from former times in quantity and content Especially the sharp confrontation of the actors and Confucianism in Northern Song dynasty shows caricature and satire of the contradictions of the society, revealing the discrepancy and pretense deeply. The conflict of the actors and Confucianism from Southern Song period to the Cheong dynasty changed from the performing style of the direct criticism of Confucianism to that of making Confucianism subsidiary subject, emphasizing the spiirit of social participation by revealing the contradictions of the society. The first error of Confucianism is the murder of Usi by Confucius and in the following Song dynasty Juhi also had a misconception about the role of actors deeply rooted in Confucianism, which brought about the protest against Confucianism, the backbone of the ruling class. The birth and growth of the actors' bantering of Confucianism developed into the spirit of social participation of the actors who bravely criticized the illnesses of the society. In this paper it could be confirmed that the actors criticized Confucianism, which couldn't be fused into the real life of people, through performance and achieved the purpose of social indictment.
        6,100원
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